What would happen if our rivers stopped flowing? Conservation groups in Texas are rallying together to ensure the future of fresh water for the economy, wildlife, and human enjoyment. National Wildlife Federation’s Myron Hess lays out the need for this type of coalition as he canoes down one of the state’s scenic rivers. With each oar stroke, Hess makes the case for the importance of preserving healthy ecosystems through clean water and the support of the Texas Living Waters Project.

The Devils River Conservancy Road Building & Drainage Workshop was a huge success! Thank you to all who joined us in learning about the benefits of road drainage features and how to implement them on various road types.#agoodroadlieseasyonthelandThanks to Steve Carson of Rangeland Hands Inc. for coming down from Santa Fen NM to lead the conversation.

Austin — September 18, 2017 — A study sponsored by Devils River Conservancy provides detailed models linking groundwater in a Texas aquifer to the surface flows in one of the state’s most pristine rivers. The study shows how karstic pathways of the Edwards-Trinity Aquifer follow the same channels as the Devils River watershed, creating natural springs that sustain the river.

“Natural springs play the major role in sustaining flows in rivers located in a semi-arid climate that experiences extended dry periods,” said Dr. Green, lead hydrologist on the project. “This study clearly illustrates the linkage of groundwater flow with surface-water flow in the Edwards-Trinity Aquifer located within the Devils River watershed.”

The headwaters to the Devils River are located in Crockett, Schleicher and Sutton counties, semi-arid landscapes with limited development. The Devils River runs 93 miles southwest into Val Verde County and Lake Amistad near the border with Mexico in southwest Texas. As a key tributary of the Rio Grande, the river provides essential freshwater flows to South Texas and the Rio Grande Valley.

The research team replicated hydraulics in the Edwards-Trinity Aquifer by coupling computer models of surface water and groundwater. The models were conceptualized and developed with a broad range of data sets, including precipitation, run-off, surface-water flow, and water extraction records. The models show, for the first time, the strong interaction between pumping groundwater and spring discharge in the river channels.

Groundwater pumping in the upper watershed is limited to domestic livestock, a few irrigation wells, and the city of Sonora. Combined, those activities account for 3,000 to 7,000 acre-feet of annual pumping, starting in the 1960s. However, the water budget of the watershed is not well constrained due to unmetered wells and unreported pumping, according to the study.

Computer models were developed to test variable precipitation and recharge in the presence of different pumping scenarios and to simulate their effects on spring discharge in the upper portion of the river. The shifting of the headwaters downstream could be explained, Green said, by diminished spring discharge associated with the onset of pumping in the 1960s. The models indicate that this pumping led to “dewatering” Beaver Lake, a former perennial lake that is about 10 miles upstream from the current headwaters located at Pecan or Hudspeth Springs. Results from the study indicate that limited extraction of groundwater can impact a river in a semi-arid climate.

“The DRC is an honest broker in the long term protection of the Devils River,” said David Honeycutt, DRC founder. “The science produced from this model illustrates that there has been significant historical drawdown on the flows of The Devils River and that any commercial harvesting of groundwater for exportation in northern Val Verde County will have an adverse effect on the necessary environmental flows to maintain the unique fauna of this special and threatened river. This model allows us to prove that fact.”

“This study provides, for the first time, the means to evaluate the relationship between groundwater pumping and spring discharge in the semi-arid environment encountered in the Edwards Plateau,” said Green. “These tools allow for water managers to evaluate water-resource strategies when administering the stewardship of this valuable resource.”

Project Overview

The Devils River Conservancy, with support from private donors, organized the Devils River Working Days project to engage landowners in evaluating aquatic invasive species populations, water quality in relation to suspended solids and sediment distribution and recreational impacts. The intention of this project was to engage landowners and stakeholders in observing and addressing challenges to the shared resource.

Summary

Observations and Suggestions

Water Clarity- There is an There is an abundance of fine sediment suspended in the Devils River and many theories as to why; recent rain events along with bank disturbances, invasive fish activity, water temperature, lack of a large flood event, or a morphological-gradient change. From the top of the river to Blue Sage we only experienced the blue water that the Devils is known for once and that was in a spring branch of the river known as Blue Hole. Observations indicate that more study is needed to understand the sediment transport and distribution processes in the Devils River.

Recreation Impacts- It is clear that recreational impacts increase dramatically below the Texas Parks and Wildlife Department Del Norte State Natural Area. In effort to address the ever growing recreational interest in the Devils River the Texas Parks and Wildlife Department is developing projects to consolidate and minimize recreational impacts along the river. Annual assessmentsof recreational impacts may be helpful in monitoring the success of these projects.

Aquatic Invasive Species- Due to water clarity issues during the project we were unable to fully evaluate the reach and damage of the aquatic invasive species in the Devils River. A different means of assessment such as targeted electroshock would be beneficial in determining the population density and reach.

Landowner Engagement- The Devils River Working Days project was successful in uniting landowners around the shared resource, identify its challenges and working together to develop solutions. We had eleven landowners participate in the Working Days project and approximately twenty landowners attend the community gathering event.

At the Texas Parks and Wildlife Commission meeting on August 20th, the Devils River Conservancy donated two kayaks to the Texas Parks and Wildlife Department for Devils River State Natural Area staff to use in conducting river patrols and outreach to river users. The DRC also donated custom wristbands, a paddler identification component of the Devils River permit system. Formed in 2011 by landowners and river users, the DRC aims to preserve and protect the Devils River and the lands within its watershed. The DRC’s donation allows TPWD to increase its management efforts and presence on the Devils River and create a pristine river recreational experience for river users.